Production and characterization of polyhydroxyalkanoates (PHA) from corn silage using Thermus thermophilus HB8

Abstract

In this study, a biodegradable copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was produced from an agricultural by-product namely corn silage through a fermentation process using Thermus thermophilus HB8. Two types of corn silage pre-treatment processes viz. deionized water treatment (unhydrolysed) and acid hydrolysis were carried out at different loadings of corn silage (6%, 12%, 24% and 48% m/v), at 70°C for 50 h. Both pre-treatments were able to produce biopolymer where 6%, 12%, 24% and 48% unhydrolyse pre-treatment yielded 12%, 20.44%, 28.42% and 18.65% PHA, respectively; 6%, 12%, 24% and 48% acidic pre-treatment yielded 42.23%, 49.53%, 56,41% and 61.32% PHA, respectively. The extracted polymer was characterized by Fourier transform infrared spectroscopy (FT-IR) and ultraviolet-visible spectroscopy (UV-Vis) to study the characteristic bands; gas chromatography was used to identify the PHA monomers of the extracted methyl esters; scanning electron microscopy (SEM) was used to study the morphology of the bioplastic products; tensile testing was used to study the tensile properties of the bioplastics.